Apparatus and method for making x-ray films

ABSTRACT

The quality of X-ray images of the softer tissues of the human body is enhanced by disposing between the subject and the X-ray image converter a bone-image compensating filter having an X-ray resistance which varies in a continuous manner over twodimensions. Specifically, the X-ray resistance of the filter varies from point-to-point in such a manner as to substantially, but not completely, equalize the total resistance to X-rays passing through adjacent portions of the subject. The filter thereby substantially suppresses the image of the skeletal structure in the resulting X-ray image and, without significant distortion, correspondingly enhances the images of the softer tissues.

United States Patent [191 Sovijarvi et al.

[ APPARATUS AND METHOD FOR MAKING X-RAY FILMS [76] Inventors: Arvi A. I. Soviiarvi, Mantytie 17 B 24, 00270 Helsinki 27; Niilo N. Jaronen, Niitykumpu 3 E 81, 02200 Niitykumpu, both of Finland [221 Filed: Nov. 30, 1971 2| 1 Appl. No.: 203,425

Related US. Application Data [63] Continuation of Ser. No. l23,366, March ll, 1971, abandoned, which is a continuation of Ser. No. 7l7,l62, March 29, I968, abandoned.

[52] US. Cl. 250/505, 250/510 [51] Int. Cl H05g 3/00 [58] Field of Search 250/86, 65 R [56] References Cited UNITED STATES PATENTS 2,405,444 8/1946 Moreau 250/86 F ORElGN PATENTS OR APPLICATIONS 1,079,448 4/1960 Germany 250/86 June 25, 1974 Primary ExaminerJames W. Lawrence Assistant Examiner-C. E. Church Attorney, Agent, or Firm-Dean S. Edmonds 5 7] ABSTRACT The quality of X-ray images of the softer tissues of the human body is enhanced by disposing between the subject and the X-ray image converter a bone-image compensating filter having an X-ray resistance which varies in a continuous manner over two-dimensions. Specifically, the X-ray resistance of the filter varies from point-to-point in such a manner as to substantially, but not completely, equalize the total resistance to X-rays passing through adjacent portions of the subject. The filter thereby substantially suppresses the image of the skeletal structure in the resulting X-ray image and, without significant distortion, correspondingly enhances the images of the softer tissues.

5 Claims, 5 Drawing Figures PATENTED JUNE 5 I974 SHEET 2 OF 2 APPARATUS AND METHOD FOR MAKING X-RAY FILMS CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation of US. Pat. Application Ser. No. 123,366 filed Mar. 11, 1971 which, in turn, is a continuation of Ser. No. 717,162 filed on Mar. 29, I968 both now abandoned.

BACKGROUND OF THE INVENTION The present invention relates to methods and apparatus for making X-ray images of the softer tissues and organs of the human body.

Techniques for obtaining high quality X-ray images of the soft organs of the human body (i.e., those organs consisting predominantly of tissues softer than bone) are of extreme importance both for research purposes and for the purpose of diagnosing and treating pathological conditions. Prior techniques for obtaining X-ray images of these organs have, however, met with only limited success.

Straightforward X-ray techniques have generally been most unsuccessful. A great part of angles of approach the vital organs are surrounded by bony tissues which have considerably greater resistance to X-rays than do the softer tissues of the organs. As a result, the X-rays show the skeletal structure well, but relatively little of the underlying internal organs.

Discontinuous and one-dimensionally varying filter structures, typically placed between the source of X- rays and the subject in order to reduce the amount of radiation received by the subject, have been employed for the purpose of obtaining improved X-ray films of the skeletal structure. See, for example, US. Pat. Nos. 2,216,326 issued to C. D. Smith; 2,405,444 issued to S. Moreau et al.; 2,506,342 issued to A. C. Burke; and 2,630,536 issued to T. Vladeff. However, insofar as is known, these arrangements have failed to produce any significant improvement in the quality of X-ray films of the softer tissues.

As a consequence of the failure of straightforward techniques, X-ray technicians have had to rely upon the use of contrast substancestsubstances having high X-ray resistance) introduced into or sprayed upon the organ to be examined. After the introduction of the contrast substance, the patient is X-rayed, and in the resulting X-ray picture the organs delineated by this substance stand out from the surrounding skeletal structure. Such substances, for example, have been introduced into the human heart by way of the associated blood vessels and have been sprayed upon the vocal chords.

There are nonetheless significant limitations upon the use of contrast materials. Typically these substances, when introduced into the blood stream, are quickly circulated into the finer veins in a very short time and the X-ray picture therefore becomes blurred. Moreover, the period of time during which organs can be observed using this technique is generally quite limited due to the fact'that the body can tolerate only limited quantities of the materials used.

SUMMARY OF THE INVENTION In accordance with the present invention, the quality X-ray images of the softer tissues of the human body are enhanced by disposing between the subject and the 1 X-ray image converter a bone-image compensating fil ter having an X-ray resistance which varies in a continuous manner over two dimensions. Specifically, the X-ray resistance of the filter varies from point-to-point in such a manner as to substantially, but not completely, equalize the total resistance to X-rays passing through adjacent portions of the subject. The filter thereby substantially suppresses the image of the skeletal structure in the resulting X-ray picture and, without significant distortion, correspondingly enhances the images of the softer tissues.

BRIEF DESCRIPTION OF THE DRAWINGS The nature, features, and advantages of the invention will appear more fully upon consideration of the various illustrative embodiments now to be described in detail in connection with the accompanying drawings.

In the drawings:

FIG. 1 is a front perspective view showing an illustrative embodiment of apparatus in accordance with the invention. This particular embodiment is specially adapted for permitting X-ray filming of the softer tissues of the human speech organs; 1

FIG. 2 is a top perspective view illustrating a bone image compensating filter specifically adapted for use in the arrangement of FIG. 1;

' FIG. 3 is a sectional view of the filter of FIG. 2 taken substantially along the line 3-3 looking in the direction of the arrows;

FIG. 4 is a top exploded view of the filter of FIG. 2; and

FIG. 5 is a top perspective view of the filter of FIG. 2 in combination with a protective casing.

DETAILED DESCRIPTION Referring now to the drawings, FIG. 1 illustrates X-ray apparatus in accordance with the invention comprising a source of X-rays 12 adapted and adjusted for producing good soft tissue X-rays disposed on one side of a human subject S and X-ray image conversion means such as an image intensifier 20 disposed on the opposite side of the subject in the path of X-rays passing through him. A bone image compensating filter 30 is also disposed on the side of the subject opposite from the source of X-rays so that it lies between the subject and the X-ray image converter and in the path of X- rays passing through the subject to the image converter. Preferably, the compensating filter is disposed adjacent the image conversion means. The image conversion means can, in general, comprise any known means for converting an invisible X-ray image into a corresponding visible X-ray image. It can, for example, comprise X-ray sensitive film or television or fluoroscopic monitoring apparatus. When an image intensifier or other monitoring device is used, a camera 22 is preferably used to record the visible X-ray images.

The bone image compensating filter comprises a plate-like structure whose X-ray resistance varies in a continuous manner from point-to-point in such a manner as to substantially suppress the image of the skeletal structure on the resulting X-ray picture. In the most practical case where the filter is composed of homogeneous material, the thickness of the filter varies from point-to-point in such a manner as to substantially, but not completely, equalize the total resistance to X-rays passing through various adjacent portions of the sub jects body.

The compensating filter can be readily fabricated by molding, milling, or casting. The desired variation in X-ray resistance can be determined empirically for subjects of the same general build by subjecting an individual of this build to a uniform intensity of X-rays and noting the variation of transmitted intensity as, for example, is shown in an X-ray film exposure. The thickness of a substantially homogeneous filter can then be varied to compensate for' the substantially greater X-ray resistance of the bony regions by making the filters correspondingly thicker in the non-bony regions in proportion to the intensity of transmitted X-rays. This variation in thickness can be effected manually by molding plastic material or precisely by a computeroperated milling machine.

The variation in filter thickness should not, of course, be so precisely correlated to the variations in transmitted intensity that even the smaller variations due to the soft organs are also eliminated. The desired result can be achieved by concentrating on the larger variations due to the bony structures and ignoring the smaller variations due to the soft organs. This approach has been found to be workable in actual practice of the inventron.

The filter can be formed of any one of the various materials conventionally employed in the previously mentioned discontinuous filters used for large area skeletal X-rays. One such material is formed of about one-third semi-hard aluminum (99.5 percent), and about two-thirds of an alloy formed of 50 percent aluminum and 50 percent copper. Alternatively, the filter can be made of synthetic resins such as elastic polyester resins (e.g., Synolite 711 (a Dutch Trademark) or a mixture of 65 percent Synolite 545.0.0.6 (also a Dutch Trademark) and 35 percent Synolite 7l 1 Preferably the filter is made from a substantially homogeneous material and the inner surface of the filter to be disposed adjacent the subject is coated with a smooth coating of resin of the type described above. Such a coating has been found to reduce the effects of surface irregularity and to reduce scattering. It thus provides sharper pictures.

In addition, the filter or its support structure should be adapted to permit the addition or removal of plates of uniform X-ray resistance covering the area to be X- rayed. The use of such plates permits a single bone compensating filter to be used for different persons having different total resistances to X-rays.

In situations where it is desired to obtain soft tissue X-rays of portions of the body capable of movement in order, for example, to study the dynamic behavior of that portion of the body, the filter structure can conveniently be adapted by extending the regions of low X-ray resistance corresponding to movable bone tissues in order that these regions substantially cover the locus of anticipated bone movements;

Arrangements should, of course, be provided for supporting the compensating filter in proper relationship with the portion of the body to be X-rayed. A specific example illustrating such a support arrangement is described in detail hereinbelow:

EXAMPLE The arrangements shown in FIGS. 1-5 are specifically adapted for use in connection with making X-ray films of the soft organs of speech. Specifically, suitable pad means 32 such as a portion of foamed plastic or the like is provided for supporting the filter means on the shoulder of the subject so as to steady compensating filter 30. In addition, the filter is held in place by support means 34.

The support means includes a headband 40 adapted to adjustably fit about the head of the subject, this headband being secured as by means of wing nuts 42 and 44 to the depending legs of a generally U-shaped member 46 having cushion pads 48 disposed at the lower ends thereof so as to prevent injury or discomfort to the subjects head.

A bracket 50 is suitably secured to the outer surface of member 46 and in turn bracket member 50 is connected with a depending curve arm 52. This arm 52 is suitably secured to the upper surface of a generally rectangular framework 54 which, as seen most clearly in FIGS. 3 and 4, includes an inwardly projecting flange portion 58 disposed around the inner periphery thereof at one edge thereof.

This framework is adapted to receive a filter means 60 the thickness of which varies as described hereinabove in accordance with the portion of the anatomy of the subject to be photographed. In this particular case, the filter takes the form of an intaglio 64 corresponding to the outer contour of the head of the subject and including an enlarged area 66 to accommodate the maximum degree of movement of the lower jaw of the subject when talking.

As seen in FIG. 1, the filter is spaced several inches or more from the subjects head when disposed in operative position.

Means for removably supporting additional filter plates of uniform thickness includes a pair of generally cylindrical pins 70 extending outwardly from the framework 54. A pair of additional filter plates 72 and 74 are illustrated, these plates being provided with spaced holes 76 and 78, respectively, for snugly receiving the pins 70. These filter plates may be formed of a material similar to the filter means 60 and may be added as required to increase the thickness of the overall filter means. The filter plates 72 and 74 are indicated as mounted in operative position in FIGS. 3 and 5. It should be understood that any additional number offilter plates may be added. These filter plates may have any desired thickness, and it has been found that filter plates of a thickness of 0.2 millimeters cause a perceivable difference in contrast.

As seen in FIG. 5, a protective casing 80 is supported adjacent filter 60 by a suitable support member 82. This protective casing includes material similar to that of filter 60 or other suitable X-ray filter substances for preventing reflected or scattered X-rays from affecting the transmitted image, thereby improving the clarity of the picture.

Using this specific embodiment of the invention, greatly improved T.V. and fluoroscopic images have been obtained, and excellent X-ray motion picture films have been taken which clearly depict details of the lips, hyoid, epiglottis, vocal cords, the ventricular (or Morganic folds), the soft palate and the entire tongue. This embodiment has been specifically applied to study speech defects and in analysis of the special features of pronunciation of foreign languages.

Other filters made in accordance with the principles of the invention can be specifically designed for use with other portions of the body. For example, a compensating filter can be designed for the heart region.

This filter permits depiction of heart chambers and the thicker blood vessels.

It is not completely understood why the compensating filter of the present invention has permitted enhancement of soft tissue images while those of the prior art have not. The present inventors believe, however, that at least two factors are involved. First, X-ray resistance of prior art filters is generally large compared to that of the soft tissues. As a result, discontinuities present in the prior art filters tend to obscure soft tissue features. Second prior art filters disposed between the source of X-rays and the subject tend to bend the X- rays at various angles thus diffusing and distorting the already low contrast features of the softer tissues. Applicants, however, rely not on any theoretical explanation, but rather the fact of the enhanced soft tissue X- rays produced using their apparatus and techniques.

In all cases, it is understood that the above-described embodiments are only illustrative of the many possible specific embodiments which can represent application of the principles of the invention. Numerous and various other arrangements can be readily devised in accordance with these principles by those skilled in the art without departing from the spirit and scope of the invention.

We claim:

1. Apparatus for producing enhanced X-ray images of the softer tissues of the human body comprising:

a source of X-rays positioned on one side of a subject for directing a beam of X-rays toward the subject;

means positioned on the side of the subject opposite said source of X-rays for receiving the X-rays transmitted through the subject and converting the resulting invisible X-ray image into a visible X-ray image;

a bone image compensating filter positioned contiguous with said image conversion means in the X-ray path between said subject and the image conversion means for substantially suppressing the image of the skeletal structure in said X-ray image, said bone image compensating filter comprising a filter having an X-ray resistance which varies in a continuous manner over two dimensions in such a manner as to substantially equalize the total resistance to X-rays passing through adjacent portions of a subject and wherein the inner surface of said filter to be disposed contiguous with the subject is a smooth coating of resin for reducing the effects of surface irregularity.

2. The apparatus of claim 1 wherein said filter is pro vided with means for removably supporting additional filter plates of uniform X-ray resistance over the portion of the subject to be observed.

3. The apparatus of claim 1 wherein said bone image compensating filter is composed of substantially homo geneous material and wherein the thickness of said filter varies from pointto-point in a manner substantially proportional to the intensity of transmitted X-rays passing through corresponding adjacent points of the subject.

4. Apparatus for producing enhanced X-ray images of the softer tissues of the human body, comprising:

a source of X-rays positioned on one side of a subject for directing a beam of X-rays toward the subject,

means positioned on the side of the subject opposite said source of X-rays for receiving the X-rays transmitted through the subject and converting the resulting invisible X-ray image into a visible X-ray image:

- a bone image compensating filter positioned contiguous with said image conversion means in the X-ray path between said subject and the image conversion means for substantially suppressing the image of the skeletal structure in said X-ray image, said bone image compensating filter comprising a filter having an X-ray resistance which varies in a continuous manner over two dimensions in such a manner as to substantially equalize the total resistance to X-rays passing through adjacent portions of a subject; a rigid framework for holding said filter means in an operative position; and

spaced support means on the framework facing the image conversion means and extending therefrom for supporting additional filter plates on said framework.

5. Apparatus as in claim 4 wherein the inner surface of said filter is coated with a smooth coating of resin for reducing the effects of surface irregularity. 

1. Apparatus for producing enhanced X-ray images of the softer tissues of the human body comprising: a source of X-raYs positioned on one side of a subject for directing a beam of X-rays toward the subject; means positioned on the side of the subject opposite said source of X-rays for receiving the X-rays transmitted through the subject and converting the resulting invisible X-ray image into a visible X-ray image; a bone image compensating filter positioned contiguous with said image conversion means in the X-ray path between said subject and the image conversion means for substantially suppressing the image of the skeletal structure in said X-ray image, said bone image compensating filter comprising a filter having an Xray resistance which varies in a continuous manner over two dimensions in such a manner as to substantially equalize the total resistance to X-rays passing through adjacent portions of a subject and wherein the inner surface of said filter to be disposed contiguous with the subject is a smooth coating of resin for reducing the effects of surface irregularity.
 2. The apparatus of claim 1 wherein said filter is provided with means for removably supporting additional filter plates of uniform X-ray resistance over the portion of the subject to be observed.
 3. The apparatus of claim 1 wherein said bone image compensating filter is composed of substantially homogeneous material and wherein the thickness of said filter varies from point-to-point in a manner substantially proportional to the intensity of transmitted X-rays passing through corresponding adjacent points of the subject.
 4. Apparatus for producing enhanced X-ray images of the softer tissues of the human body, comprising: a source of X-rays positioned on one side of a subject for directing a beam of X-rays toward the subject, means positioned on the side of the subject opposite said source of X-rays for receiving the X-rays transmitted through the subject and converting the resulting invisible X-ray image into a visible X-ray image: a bone image compensating filter positioned contiguous with said image conversion means in the X-ray path between said subject and the image conversion means for substantially suppressing the image of the skeletal structure in said X-ray image, said bone image compensating filter comprising a filter having an X-ray resistance which varies in a continuous manner over two dimensions in such a manner as to substantially equalize the total resistance to X-rays passing through adjacent portions of a subject; a rigid framework for holding said filter means in an operative position; and spaced support means on the framework facing the image conversion means and extending therefrom for supporting additional filter plates on said framework.
 5. Apparatus as in claim 4 wherein the inner surface of said filter is coated with a smooth coating of resin for reducing the effects of surface irregularity. 